This paper analyzes the changes in Japan’s regional approach to Southeast Asia, evolving from a focus on economic support to encompass both economic and security assistance, with the strategic application of Official Development Assistance (ODA) as a case study. Since the early 1950s, Japan’s approach to Southeast Asia aimed at post-war reintergration into the international community and economic rehabilitation, mainly through quasi-war reparations in the form of economic aid. However, Japan’s profit-oriented approach faced various criticisms in the 1970s, notably inciting anti-Japanese centiments within the region. To address these issues, Japan announced the “Fukuda Doctrine,” establishing a foundation for a more structured, long-term regional strategy with both quantitative and qualitative enhancements in economic assistance.
After the Cold War, Japan began to recognize the rise of non-traditional security threats in Southeast Asia, particularly piracy and armed robbery issues, and the lack of regional leadership to address them. Since the 2000s, Japan has called for multilateral security cooperation and provided bilateral support for maritime law-enforcement capabilities to help maintain the stability in the regional maritime domain. Around 2010, China began asserting its maritime interests more aggressively, leading to escalated territorial disputes with Japan and Southeast Asian states. Against this backdrop of shifting security dynamics in the maritime domain, Japan has strategically employed ODA to support the maritime law enforcement capabilities of key Southeast Asian states, particularly the Philippines, Vietnam, Indonesia, and Malaysia. Through these efforts, Japan has promoted maritime stability in Southeast Asia and strengthened security cooperation beyond economic relations, advancing its “Free and Open Indo-Pacific” vision.